body {
  background-image: url(obrazki/deepslate.png);
  color: black;
  font-family: Verdana;
  margin: 0;
  overflow: hidden;
}

header {
  background-image: url(obrazki/logo.gif), url(obrazki/kit.gif);
  background-size: 842px 108px, cover;
  background-position: center;
  background-repeat: no-repeat;
  background-color: white;
  display: block;
  width: 98.9%;
  margin: 3px;
  border-radius: 25px;
  border: gray 5px solid;
  position: absolute;
}

.glowne{
  height: 500px;
  border-radius: 25px;
  border: gray 5px solid;
  background-color: white;
  }

#xd{
  width: 100%;
  height: 150px;
}
  
#lewy{
  width: 25%;
  margin-right: 31px;
  margin-top: 20px;
  float: left;
  }
  
#prawy{
  width: 25%;
  margin-left: 31px;
  margin-top: 20px;
  float: left;
  }
  
#srodek{
  width: 44%;
  margin-top: 20px;
  float: left;
}